The present invention relates to an automatic transmission control unit.
There exists a vehicle mounted with a shift-by-wire system equipped with an actuator 130 that changes a travel range of a vehicle automatic transmission 140, and a shift-by-wire control circuit (referred to as an SBW-ECU below) 110 that controls the actuator 130 (with a motor 131) based on a required range selected by a driver, as shown in FIG. 8. An automatic transmission control circuit (referred to as an AT-ECU below) 120 is mounted in the vehicle that controls various valves of a hydraulic control device of the automatic transmission 140. The actuator 130, the SBW-ECU 110, and the AT-ECU 120 are separately accommodated in a case, with the SBW-ECU 110 and the AT-ECU 120 connected via connectors 111, 121 by harnesses 102, 103 to an engine ECU 100 that controls an engine. The SBW-ECU 110 and the actuator 130 are connected via connectors 112, 132 by a harness 113. The engine ECU 100, the SBW-ECU 110, and the AT-ECU 120 are connected to an onboard communication system CAN (Controller Area Network) 101, and are capable of communicating with one another according to CAN protocol. The SBW-ECU 110 includes a power source, a motor CPU, a power source CPU, a CAN interface, a motor drive circuit, a shift interface, and an SBW-specific vehicle interface, and is also connected with a shift lever 115 via the connector 111. The AT-ECU 120 includes a power source, an AT CPU, a CAN interface, and an AT interface, and is connected with the automatic transmission 140.
However, since the actuator 130, the SBW-ECU 110, and the AT-ECU 120 are separately accommodated in the case according to the above conventional shift-by-wire system and the like, respective onboard spaces must be provided, which causes an increase in the overall size of the system. In addition, the SBW-ECU 110 sends a drive current of the actuator 130 to an internal layer pattern of a printed circuit board, thereby increasing the size of the printed circuit board and the overall size of the system as a consequence. The actuator 130, the SBW-ECU 110, and the AT-ECU 120 being separately accommodated in a case, and the SBW-ECU 110 and the AT-ECU 120 having similar circuit functions including power sources and CAN interfaces, also results in an increased number of parts and manufacturing costs.
A shift-by-wire system that integrates the actuator and the SBW-ECU has been proposed in Japanese Patent Application Publication No. JP-A-2007-10042 as a countermeasure. According to this shift-by-wire system, the actuator and the SBW-ECU are stored in one case, which enables downsizing.